The response regulator-like protein Pos9/Skn7 of Saccharomyces cerevisiae is involved in oxidative stress resistance

Abstract

We have isolated mutants of Saccharomyces cerevisiae with an increased sensitivity to oxidative stress. All pos9 mutants (pos for peroxide sensitivity) were hypersensitive to methylviologene, hyperbaric oxygen or hydrogen peroxide, but grew similarly to the wild-type under all other conditions tested. Isolation and sequencing of the respective POS9 gene revealed that it was identical to SKN7. The predicted Skn7/Pos9 protein possesses a domain with high homology to prokaryotic response regulators. These regulatory proteins are part of a simple signalling cascade termed a "two-component system", where a phosphorylation signal of a histidine kinase is transferred to a conserved aspartate residue of the response regulator. To test the functional role of the respective aspartate residue of Skn7/Pos9 protein in oxidative stress, we mutagenized this residue in vitro to alanine, arginine and glutamate. Only the glutamate allele (D427 to E) was able to rescue the hydrogen peroxide-sensitivity of pos9 mutants. By fusion experiments with the Gal4 DNA-binding domain we identified the isolated response regulator-like domain as a novel eukaryotic domain sufficient for gene activation. Whereas this hybrid protein activated transcription of a lacZ reporter gene under aerobic conditions, no activation was observed under anaerobic conditions, indicating that the response regulator domain is involved in a signalling reaction. Two-hybrid investigations also suggest an oligomerization of the Pos9 protein. Our results indicate that a two-component system is involved in the oxidative-stress response of yeast.

Chronological and replicative life-span extension in Saccharomyces cerevisiae by increased dosage of alcohol dehydrogenase 1

“…In S. cerevisiae, adaptation to H 2 O 2 correlates with the rapid induction of a so-called H 2 O 2 stimulon of several hundred proteins (Godon et al, 1998) and the repression of many others. This adaptation is orchestrated by the action of several transcriptional regulators, such as Msn2/Msn4 (Hasan et al, 2002), Yap1 and Skn7 (Kuge & Jones, 1994;Krems et al, 1996). To our knowledge, there are no reports connecting Sir2p with the activation of such transcription factors in yeast.…”

Stress‐activated signalling pathways in yeast

“…Other signalling pathways which may regulate Yap1 have not been identified. However, in a screen for peroxide sensitive mutants a gene called POS9/SKN7, which is predicted to have a role in signalling, has recently been found (Krems et al 1996). POS9/SKN7 encodes a protein with homology to bacterial response regulators implying that a two-component-like signal system may be operating in the budding yeast oxidative stress response.…”

“…POS9/SKN7 encodes a protein with homology to bacterial response regulators implying that a two-component-like signal system may be operating in the budding yeast oxidative stress response. Furthermore, evidence indicates that Pos9/ Skn7may be acting in the same pathway as Yap1: Pos9/ Skn7, like Yap1, is required for the induction of TRX2 and TRR1 during oxidative stress and a pos9 yap1 double mutant is no more sensitive to H 2 O 2 than either single mutant (Krems et al 1996;Morgan et al 1997). The existence of a receiver domain in Pos9/Skn7 suggests that the protein responds to phosphorylation by a histidine kinase.…”

Signal transduction via the histidyl‐aspartyl phosphorelay

“…In S. cerevisiae, the Skn7 protein has a response regulator type domain that is homologous to heat shock transcription factors. While the upstream histidine kinase remains elusive, the function of Skn7 has recently been determined to be involved in oxidative stress resistance (Krems et al 1996). In Neurospora crassa, a light-dependent system involving an aspartyl phosphoprotein (WC-1/WC-2), and a gene encoding a hybrid histidine kinase, NIK, has been identified.…”